1. Technical Field
The present invention relates to light receiving and emitting devices.
2. Related Art
In a semiconductor light emitting device used in optical communications and the like, adjustment of the amount of light etc. is performed by extracting part of light emitted from the device with a semi-transmissive mirror and a diffraction element placed outside the device and detecting the light by a light receiving element.
For example, in JP-A-10-3691, an optical pickup device that makes light from a laser diode branch off by a spectroscopic prism or the like and includes a monitoring photodiode detecting the branched light has been proposed.
On the other hand, in recent years, a high-brightness laser device with excellent color reproducibility has been expected to be used as a light emitting device for a light source of a display device such as a projector or a display. However, when a laser diode is used in the display device, adequate brightness may not be obtained unless a plurality of laser diodes are used. Also in such a display device, in order to reduce unevenness of brightness, it is necessary to adjust the amount of light by detecting the amount of light of the light emitting device.
However, since a light emitting element and a light receiving element are separately provided in the method disclosed in JP-A-10-3691, the method needs an extra optical element such as a spectroscopic prism or the like. This results in an increase in the number of parts and makes it difficult to realize miniaturization. Moreover, to use a laser diode in the display device, the amounts of light of a plurality of laser diodes have to be detected individually, but it is difficult to provide the light receiving element for each of the laser diodes.